Interlock arrangement for a circuit breaker having a stored-energy closing device



reb. 12, 1957 G. RUDOLPH 2,781,427

INTERLOCK ARRANGEMENT FOR A CIRCUIT BREAKER HAVING A STORED-ENERGYCLOSING DEVICE Flled Feb 3, 1955 2 Sheets-Sheet 1 lilllll ln Inventor:Geofge Ru olph,

JDH r' HiA'btOTfieg.

1957 s. RUDOLPH 2,781,427

INTERLOCK ARRANGEMENT FOR A CIRCUIT BREAKER HAVING A STORED-EN RGYCLOSING DEVICE Flled Feb 3, 1955 2 Sheets-Sheet 2 In e n tor:

George Ru olph, b5 W His torneg.

United States Patent M INTERLOCK ARRANGEMENT FOR A CIRCUIT BREAKERHAVING A STORED-ENERGY CLOS- ING DEVICE.

George Rudolph, Broomall, Pa., assignor to General Electric Company, acorporation of New York Application February 3, 1955, Serial No. 485,997

12 Claims. (Cl. 200-50) This invention relates to an interlockarrangement for a cubicle-enclosed, electric circuit breaker of the typehaving a stored energy device for effecting closing thereof.

If an attendant wishes to remove a cubicle-enclosed circuit breaker fromits cubicle so as to permit inspection or repair of its internal parts,he first trips the breaker to its open circuit position. Interlockswhich insure such tripping are well known. For most types of breakers,once the breaker has been tripped open, the attendant is then free tosafely remove it from its cubicle and to safely perform whatever repairsor inspection operations are desired. However, if the breaker is of thetype which has a stored energy closing device, it is likely that theclosing device will be charged at the time the breaker is removed fromits cubicle even though the breaker is tripped open. To safeguardagainst accidental discharge of such a stored energy closing deviceduring subsequent repair or inspection operations, it has been customaryto manually block the closing device in its charged position before thebreaker is withdrawn from its cubicle. This procedure is disadvantageousbecause it depends for its reliability upon the skill and memory of theattendant.

Thus, an object of my invention is to provide, in a circult breakerhaving a stored-energy closing device, means which acts automatically toinsure against accidental discharge of the closing device during thetime the breaker is being inspected or repaired.

A further object is to provide a simple, inexpensive and reliableinterlock which prevents removal of the circuit breaker from itsenclosing cubicle while the stored-energy closing device is charged.

In accordance with one form of my invention, the circuit breaker isprovided with a movable interference men1- her which is operable in ablocking position to prevent withdrawal of the breaker from itsenclosing cubicle and is operable in a disabled position to permit saidwithdrawal. This interference member is controlled by a linkage which isoperably connected to the stored-energy closing device of the circuitbreaker. So long as the closing device is charged, the interferencemember remains in its blocking position, but when the closing device isdischarged, the linkage responds by removing the interference memberinto its disabled position, thereby permitting withdrawl of the breakerbut only when the closing device is discharged.

Where a stored-energy closing device is utilized, it is conventional toprovide a charging motor which automatically recharges the closingdevice as soon as it is discharged. In accordance with another aspect ofmy invention, this charging motor is rendered inoperative in response topartial Withdrawal of the breaker from its cubicle, whereas theinterference member is arranged to block circuit breaker movement onlyafter additional withdrawal movementhas taken place. Thus, when thecircuit breaker is withdrawn into its blocked position, the chargingmotor has already been rendered inoperative. As a result, when theclosing device is then discharged to disable the interference member,the closing device remains safely discharged and unaffected by thecharging motor.

For a better understanding of my invention, reference may be had to thefollowing specification taken in connection with the accompanyingdrawing wherein Fig. 1 shows a cubicle-enclosed circuit breaker partlyin section and embodying my invention. A portion of the circuit breakeris shown in schematic form. Fig. 2 is an enlarged perspective view of aportion of the mechanism shown in Fig. 1, and Fig. 3 is a schematicdiagram illustrating the manner in which I control the motor forcharging the circuit breaker closing device.

Referring now to Fig. 1, there is shown a circuit breaker 10 which ismounted on suitable wheels 9 so that it is capable of horizontalmovement into and out of a connected position within an enclosingcubicle 12. The breaker 10 is provided with the usual disconnectcontacts 13 and 14 which, in the connected position shown in Fig. l, areplugged into mating terminal structures 15 and 16 carried by the cubicle12. In this connected position, the breaker is adapted to control apower circuit 17 which extends between the terminal structures. Thiscircuit control is effected by means of a pair of relativelymovableinterrupting contacts 18 and 19. One of these contacts 18 is pivotallymounted at 18a and is biased to the open circuit position shown by asuitable spring 20.

For moving the contact 13 to closed circuit position, I have shown aconventional trip free operating mechanism M which comprises a pair oftoggle links 21 and 22 pivotally joined together at a knee 23. One ofthe toggle links 21 is pivotally connected at its opposite end tomovable contact 18 Whereas the other of the toggle links 22 is connectedby pivot pin 22a to the upper end of a guide link 24. This guide link 24is pivotally supported at its lower end on a fixed fulcrum 26. The pivotpin 22a carries a latch roller 28 which cooperates with a suitable triplatch 30. So long as the trip latch 30 remains in the latched positionshown, the toggle 21, 22 is capable of transmitting thrust to themovable contact 18. Thus, when the knee 23 is lifted from the positionshown in Fig. 1, the toggle 21, 22 is extended and drives the movablecontact 18 toward the closed circuit position. This lifting of the knee23 is accomplished by the action of a suitable rotatable cam 35cooperating with the usual roller 36 which is mounted at the knee 23.Preferably, the cam 35 is arranged to drive the toggle 21, 22 slightlyovercenter and against a stop 37 so that the movable contact will beheld in closed circuit position even when the cam is returned to itsoriginal position shown in Fig. 1.

Should the latch 30 be tripped when the breaker is closed, or evenduring the closing stroke, the toggle 21, 22 will be renderedinoperative to transmit thrust to the movable contact 18. As a result,the opening spring 20 will be free to drive the movable contact 18 toits open :circuit position. As long as the latch 30 is held tripped, thetoggle 21, 22 will remain inoperative to transmit closing thrust to themovable contact 18. A suitable resetting spring 38 cooperates with theguide link 24 to reset the mechanism to the latched position after ithas been tripped.

For rotating the cam 35 so as to drive the contact 18 toward closedcircuit position, I have provided in the illustrated embodiment a storedenergy closing device of the kind disclosed and claimed in U. S; PatentNo. 2,667,076, issued to John A. Favre and assigned to the assignee ofthe present invention. It is to be understood that the particular typeof closing device illustrated has been selected simply because itreadily lends itself to an understanding of the invention. The inventionis equally applicable to other types of stored-energy closing devices.

As seen in Figs. 1 and 2, the disclosed closing device comprises a heavycompression spring 45, suitably sup- Patented Feb. 12, 1957,

3 ported at its upper end on a pivotally mounted bracket 46. At itslower end the spring 45 is coupled to an adapter 47 which is pivotallymounted on a crank arm 48. This crank arm 33 is keyed to a rotatableshaft 50 which is iournaled in spaced side frames 52 and 53. Asindicated in Fig. l, the closing cam is arranged to be driven by thisrotatable shaft 50. Also keyed to the rotatable shaft is a chargingmember 55 which is arranged to be driven by a suitable electric motor.This motor is not shown in Figs. 1 or 2 but is schematically shown at 56in Fig. 3. As shown in Fig. 2, power from the charging motor istransmitted to the charging member 55 through a gear train 60, a drivingshaft 61, an orbital member 63 keyed to the shaft 61, and a driving pin64 carried at the outer end of the orbital member 63. When the drivingshaft 61 isrotated counter-clockwise from the position shown in Fig. 2,the driving pin 64 acting through the charging member 55 and shaft 50rotates the crank 48 counterclockwise to charge the spring 45. Thiscounter-clockwise charging motion of crank 48 continues until theorbital member 63 moves into or 'just short of its dead center positionwith respect to the charging member 55. At this approximate dead centerposition, which is shown in Fig. l, movement of the orbital member isstopped by a suitable limit switch which opens the energizing circuitfor the charging motor '56. This is shown most clearly in Fig. 3 whereinthe motor 56is shown connected in circuit with "a suitable power sourcesuch as a battery '72. The limit switch, which is shown at is controlledby a cam 71 which is operatively connected in a suitable manner to thedriving shaft'fil and is shaped to open the switch 70 as theabove-mentioned dead center position is approached. The closing spring45 is then fully charged and in a condition to drive the circuit breakertoward a closed position should the spring be subsequently discharged.As explained more fully in the above-mentioned Favre patent, thisdischarge action is normally effected by energizing the motor so as todrive the orbital member 63 over center. This motor energization iseffected by a suitable switch such as the push button 73 of Fig. 3. soonas the energized motor drives the crank 63 counterclockwise slightlybeyond dead center, the closing spring 45 rapidly releases its energyand drives the shaft 50 clockwise at high speed, thereby driving thebreaker toward closed position.

The above described discharge of the'closing spring 45 also drives theorbital member 63 counter-clockwise from the position of Fig. 1 to theposition of Fig. 2. A suitable overrunning clutch indicatedschematically at 74 is provided to permit shaft 50, during springdischarge, to move at high speed free from the restraining influence ofthe gear train dtl. During this period, the shaft 6'1 overruns the gear76, which is mounted for rotation thereon. When the parts have assumedthe position of Fig. 2 the limit switch cam 71 is arranged to permit thelimit switch to close thereby automatically energizing the motor andcausing it to recharge the closing spring 45. As previously explained,this recharging operation continues until the parts approach the deadcenter position of Fig. l, at which time the limit switch 70 opens themotor energizing circuit.

If an attendant wishes to remove a cubicle-enclosed circuit breaker fromits cubicle ,so as to permit inspection or repair of its internal parts,he firsttrips the breaker to open circuit position. interlocks whichinsure such tripping are well known, and any suitable conventional formof such an interlock can be 'used with my breaker. An example of such aninterlock is shown in Fig. 2 of U. S. Patent No. 2,702,324, issued to W.J. Donaldson and assigned to take assignee of the present invention.interlocks such as those shown in the Donaldson patent operate bymaintaining the breaker trip latch, such as my latch 30 in a trippedposition during the withdrawal operation. For most types of breakers,once the breaker has been tripped open, the attendant is then free tosafely removed it from its cubicle and to safely perform whatever repairor inspection operations are desired. However, if the circuit breaker isof a type which has a stored-energy closing device, as described above,it is likely that the closing device will be charged at the time thebreaker is removed from its cubicle even though the breaker is trippedopen. To safeguard against accidental discharge of such a stored energyclosingdeviceduring subsequent repair orinspection operatrons, it hasbeen customary to manually block the closing device in its chargedposition before the breaker is with drawn from its cubicle. Thisprocedure is disadvantageous because it depends forits reliability uponthe skill and memory of the attendant.

To overcome the above-noted disadvantages, I have provided, in thedisclosed circuit breaker 10, an interlock arrangement 79 which isautomatic in operation and does not depend for its reliability upon theskill or memory of the attendant. To this end, the interlock arrangement79 prevents v.rernoval of the breaker from its cubicle 12 while .theclosing device 45 is in a charged condition, and only after the closingdevice has been discharged, may the breaker be removed. Moreparticularly, this interlock arrangement 79 comprises a verticallyslidable interference member 84} which is suitably biased into ablocking position such as shown in Fig. l, as by a spring 81. Thisinterference member is arranged to remain in its blocking position solong as the .circuit breaker closing spring 45 is charged. If withdrawalof the breaker is attempted with this interference member 80 in itsblocking position, the interference member will engage a fixed stop 82projecting from the bottom of the cubicle 12, and further withdrawalwill be prevented. Thus, so long as the closing spring 45 is charged,complete withdrawal of the breaker from the cubicle will be effectivelyprevented.

As best illustrated in Fig. 2, the interference member 80 is controlledby a linkage 84., 85, 86 which responds to discharge of the breakerclosing spring 45 to lift the interference member into a disabledposition Where it clears the stop 82. 'With the interference member sodisabled, complete withdrawal is then permitted. The controlling linkagefor the interference member comprises a shaft rotatably journaled in theside frame 52, a control link 84 pinned to one end ofsha'ft 85 and acammember 86 pinned to the other end of the shaft 85. The link 84 .ispivotally joined to the interference member 80. The cam .86 is arrangedto be engaged and controlled by the orbital member 63. Moreparticularly, when the orbital member 63 moves into .thexposition ofFig. 2 in response :to discharge of the closing spring 45, earn 86 isrotated to lift the interference member to its disabled position. Whenthe orbital member 63 is moved counterclockwise beyond the position ofFig. 2 so as to recharge the closing spring 45, the interference memberis permitted to return to .its blocking position under the influence ofthe .biasing spring 81. Thus, only when the closing spring 45 isdischarged, is removal of the breaker permitted.

As previously described, under normal conditions, the charging motor isarranged to automatically recharge the closing spring 45 as soon as itis discharged. In accordance with the present invention, this chargingmotor is rendered inoperative in response to a partial withdrawal of thebreaker from its cubicle 12, whereas the interference member 80 isarranged to block circuit breaker movement only after additionalwithdrawal movement has taken place. For example, referring to Fig. 3,when the circuit breaker is withdrawn to an intermediate position A. themotor energizing circuit is rendered inoperative by the opening of asuitable position-responsive disabling swith 90. In the illustratedembodiment, this disabling switch '90 is spring-biased toward openposition but is prevented from opening'until its projecting portion 91is moved past the outer edge of a suitable stationary cam 92. Thus, whenthe 'breaker'is further withdrawn into its blocked position indicated byB in Fig. 3, the motor is no longer operative to automatically rechargethe closing spring after its discharge. Thus, once the attendant movesthe circuit breaker into the blocked position B and discharges theclosing spring, the closing spring remains safe- 1y discharged andunaffected by the charging motor.

Since the motor is disabled when the breaker occupies the blockedposition B, discharge of the closing spring 45 is manually effected bymeans of a suitable tool (not shown) applied to the triangular end 93 ofthe driving shaft 61. By utilizing such a tool, the attendant maymanually move the orbital member 63 over center and permit the closingsprings to discharge as desired. The conventional interlock (not shown)which holds the latch 30 in tripped position assures that such dischargeof the closing springs will not close the breaker.

It is to be understood that the illustrated closing device is simply oneexample of closing devices to which my invention is applicable. Foranother example, reference may be had to Favre Patent No. 2,674,345,wherein a latch is utilized to hold the closing device in chargedposition. The particular type of closing device shown has been selectedsimply because it readily lends itself to an understanding of theinvention and not because it has any particular tendency to becomeaccidentally discharged. As a matter of fact, even without my interlockarrangement, the possibilities that the illustrated closing device willbe accidentally discharged are quite remote because of the relativelyinvolved series of steps required to discharge the closing device whenthe breaker is removed from the cubicle.

While I have shown and described a particular embodiment of myinvention, it will be obvious to those skilled in the art that variousvchanges and modifications may be made without departing from myinvention in its broader aspects and I, therefore, aim in the appendedclaims to cover all such changes and modifications as fall within thetrue spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a switchgear unit, a cubicle, a circuit breaker movable into andout of said cubicle and comprising a closing spring which isdischargeable to close the circuit breaker, the circuit breaker being ofthe type which can be tripped free of its closing spring and in whichmeans are provided for insuring tripping before withdrawal of thebreaker from said cubicle, an interference member operable in a blockingposition to prevent withdrawal of said breaker from said cubicle andmovable into a disabled position to permit said withdrawal, means formaintaining said interference member in its blocking position while saidclosing spring is charged and means responsive to discharge of saidclosing spring for moving said interference member into its disabledposition whereby to permit withdrawal of said breaker when said springis discharged.

2. In a switchgear unit, a cubicle, a circuit breaker movable into andout of said cubicle and comprising a closing spring which isdischargeable to close the circuit breaker, a movable interferencemember biased toward a blocking position wherein said member is operableto prevent withdrawal of said breaker from said cubicle while saidspring is charged and movable to a disabled position to permitwithdrawal of said breaker, and means responsive to discharge of saidspring for moving said interference member into its disabled positionwhereby to permit withdrawal of said breaker from said cubicle.

3. In a switchgear unit, a cubicle, a circuit breaker movable into andout of said cubicle and comprising a stored-energy closing device whichis dischargeable to close the circuit breaker, interlock means forpreventing withdrawal of said breaker from said cubicle while saidclosing device is charged, and means responsive to discharge of saidclosing device for disabling said interlock means whereby to permit saidbreaker to be withdrawn from said cubicle while said closing device isdischarged.

4. In a switchgear unit, a cubicle, a circuit breaker movable into andout of said cubicle and comprising a stored-energy closing device whichis dischargeable to close the circuit breaker, interlock means forinsuring discharge of said closing device before said breaker iscompletely withdrawn from said cubicle comprising a linkage carried bysaid breaker and having one end thereof 0peratively connected to saidclosing device, the other end of said linkage being provided with amember movable relative to said breaker and located to engage a portionof said cubicle when said breaker is partially withdrawn from saidcubicle with its closing device charged.

5. In a switchgear unit, a cubicle, a circuit breaker movable into andout of said cubicle and comprising a closing spring which isdischargeable to close the circuit breaker; a spring controlling memberwhich is movable into a predetermined first position to charge saidspring, is movable out of said first position to permit said spring todischarge, and is movable into a predetermined second position inresponse to discharge of said spring; an interference member operable ina blocking position to prevent withdrawal of said breaker from saidcubicle and movable to a disabled position to permit said withdrawal,and means operable in response to movement of said spring controllingmember into said second position for moving said interference memberinto its disabled position whereby to permit withdrawal of said breakerwhen said spring is discharged.

6. In a switchgear unit, a cubicle, a circuit breaker movable into andout of said cubicle and comprising a closing spring which isdischargeable to close the circuit breaker, an interference memberoperable in a blocking position to prevent withdrawal of said breakerfrom said cubicle and movable into a disabled position to permit saidwithdrawal, a spring controlling member which is movable from a first toa second position in response to discharge of said closing spring, meansfor maintaining said interference member in its blocking position whilesaid spring is charged, and actuating means operable in response tomovement of said spring controlling member into said second position formoving said interference member into its disabled position whereby topermit withdrawal of said breaker but only when said spring isdischarged.

7. The combination of claim 6 in which said actuating means comprises acam member which is operable by said spring controlling member duringmovement thereof into said second position and means responsive tooperation of said cam member for moving said interference member intoits disabled position.

8. In a switchgear unit, a cubicle, a circuit breaker movable into andout of said cubicle and comprising a closing spring which isdischargeable to close the circuit breaker, an interference memberoperable in a blocking position to prevent withdrawal of said breakerfrom said cubicle and movable into a disabled position to permit saidwithdrawal, motor means which is operable both to charge said spring andto effect discharge thereof, means for rendering said motor inoperablein response to partial withdrawal of said breaker from said cubicle,manually actuable means for discharging said spring when said motor isinoperable, and means responsive to discharge of said spring from movingsaid interference member to its disabled position.

9. In a switchgear unit, a cubicle, a circuit breaker movable into andout of said cubicle and comprising a closing spring which isdischargeable to close the circuit breaker, an interference memberoperable in a blocking position to prevent withdrawal of said breakerfrom said cubicle and movable into a disabled position to permit saidwithdrawal, a spring controlling member, motor means which is operableto move said spring controlling member into a predetermined position tocharge said spring and is operable to move said member out of saidpredetermined position to permit discharge of said spring, means forrendering said motor means inoperable in response to partial withdrawalof said breaker from said cubicle, manually actuable means fordischarging said spring when said motor is inoperable, means formaintaining said interference member in its blocking position while saidspring is charged, and means operable in response to discharge of saidspring for moving said interference member to its disabled positionwhereby to permit complete withdrawal of said switchgear unit from saidcubicle.

10. In a switchgear unit, a cubicle, a circuit breaker movable into andout of said cubicle and comprising a stored-energy closing device whichis dischargeable to close the breaker, motor means which is normallyoperable to automatically recharge said closing device in response toits discharge, means responsive to partial withdrawal of said breakerfrom said cubicle to render said motor means inoperative, interferencemeans operable after further withdrawal of the breaker to block completewithdrawal of the breaker while said closing device is charged, andmeans responsive to discharge of said closing device for disabling saidinterference means thereby to permit complete withdrawal of the breakerwhen said closing device is discharged.

11. In a switchgear unit, a cubicle, a circuit breaker movable into andout of a connected position within said cubicle, a stored-energy closingdevice which is dischargeable to close the breaker, motor mean which isnormally operable to automatically recharge said closing device inresponse to its discharge, an interference member operable in a blockingposition to prevent Wlth drawal of said breaker more than apredetermined distance from its connected position and movable to adisabled position to permit additional withdrawal, means responsive towithdrawal of said breaker aidistance les than said predetermineddistance for rendering said motor means inoperative, and meansresponsive to discharge of said closing device for moving saidinterference member to its disabled position whereby to permit saidadditional withdrawal of said breaker when said closing device isdischarged.

12. The apparatus of claim 4 in combination with motor means normallyoperative to automatically recharge said stored-energy closing device inresponse to discharge thereof, switch means for rendering said motormeans inoperable in response to withdrawal of the breaker from saidcubicle to an extent less than that required to render said. interlockmeans ciiective.

No references cited.

